1. Field of the Invention
This invention relates to well tools and more particularly to devices for temporarily stopping well tools at known checkpoints in their movement through well flow conductors.
2. Description of the Prior Art
In performing operations in wells through use of pumpdown tools and techniques wherein well tools are moved into and out of wells by circulating fluids such as water or oil through the well, it is often desirable to know the location of the tools in the system. In the past, the circulating medium has been measured, and this volume together with the unit volume of the well flow conductor has been used to roughly compute the location of the tools in the well during such operations. Such indications are highly inaccurate because, as is well known, the pumpdown tools have of necessity a built-in bypass which allows fluids to pass through or around them. Such bypass is necessary in case the tool train becomes fouled in the well and another tool train must be sent down to free and retrieve the fouled tool train. This second train can be pumped into the well only if fluids will pass through or around the first tool train. Thus, and especially in wells where the tool trains must be pumped as much as 5 or 10 miles to the lower portions of the wells, the location of such tool trains may not be determinable within several thousand feet.
Related co-pending application for WELL TOOL STOPPING DEVICES, SYSTEMS AND METHODS mentioned above discloses devices which are made up in the flow conductors of wells at known locations therein and which have remotely actuable lug means which are controlled from the surface. These lug means when in normally retracted position do not protrude into the bore of the flow conductor and, so, will allow well tools to move therepast unhindered. When actuated to tool-engaging position, these lugs project into the bore of the flow conductor and will cause well tools to lodge thereagainst. Since the tools are moved through the flow conductor by force of pumped fluids, the stoppage of the tools restricts flow appreciably and, thus, causes an increase in pump pressure. This increase in pressure is observed at the surface, and it is thereby known that the tools have reached such checkpoint. The lugs are then retracted and the tools allowed to pass through and beyond that checkpoint. The next such tool stopping device is then actuated so that the tools will be stopped, thereby causing another increase in pump pressure, indicating arrival of the tools thereat.
Such devices are intended for stopping of ordinary tools. However, if the tool train to be stopped includes, for instance, a safety valve, or the like, which is being run into the well on a running tool having a shear pin which releases the safety valve responsive to one or more jarring impacts, the shear pin may become sheared and the safety valve lost in the well as a result of the tool train being stopped at one or more such tool stopping devices.
The present invention is embodied in a well tool stopping device specifically designed to stop tool trains which include a running tool or similar tool having a shear pin. This tool train is equipped with key means having an abrupt stop shoulder thereon and located in the train at a locaton above the running tool. These keys may be like those disclosed in U.S. Pat. No. 2,673,614. The tool stopping device preferably has a full-opening bore and a surrounding abrupt stop shoulder like that also disclosed in U.S. Pat. No. 2,673,614. Thus, when the keys on the tool train enter the device, their stop shoulders will engage to arrest movement of the train.
To release the tool train for movement beyond the device at which it stopped, the device is provided with lugs which are actuated remotely to contracted position to depress the keys and disengage their abrupt shoulders from those of the device and permit the tool train to move therebeyond. This tool stopping device does not restrict the bore of the flow conductor even when the lugs are in their innermost position.
Related prior art includes the following patents.
U.S. Pat. No. 2,673,614 PA1 U.S. Pat. No. 3,696,868 PA1 U.S. Pat. No. 3,937,279 PA1 U.S. Pat. No. 4,114,694
U.S. Pat. No. 2,673,614 issued to Ira A. Miller on Mar. 30, 1954 discloses a full opening receptacle having an abrupt stop shoulder surrounding its bore, which shoulder is engageable by a corresponding abrupt stop shoulder on keys carried on a lock device installable in the receptacle. The lock device is lowered in the well and will stop when it encounters the receptacle for which it is fitted. This receptacle has no means for then releasing the keys to permit the lock device to move therepast.
U.S. Pat. No. 3,696,868 issued to Donald F. Taylor, Jr. on Oct. 10, 1972 discloses a downhole safety device having a piston actuable remotely from the earth's surface for holding the safety device open to permit production therethrough. A control mechanism at the surface maintains control pressure on a fluid line communicating with the piston and will respond to an emergency condition by bleeding the pressure from the control line and allowing the safety device to shut off well flow at its subsurface level.
U.S. Pat. No. 3,937,279 issued to George M. Raulins on Feb. 10, 1976 discloses a downhole well device which has a retractable stop shoulder. An internal sleeve has collet fingers on one end thereof, and each of these fingers has an internal boss thereon. In one position of the sleeve, the fingers inherently assume a position in which their bosses do not project into the bore of the well flow conductor. The sleeve is shiftable to its other position in which its fingers are cammed inwardly to a position in which their bosses project into and restrict the bore of the flow conductor and are able to stop well tools which might engage them. This sleeve is not remotely shiftable.
U.S. Pat. No. 4,114,694 issued to Robert W. Dinning on Sept. 19, 1979. This patent discloses a downhole device having a body with a lateral window, a lug carried in the window and a hoop surrounding the lugs (FIG. 11) so that it projects through the window and is engaged in a recess in a plug in the bore of the body to hold the plug in place. A piston is movable by a spring, after the pressure in the flow conduit has been built up and then decreased, to move the hoop to a neutral poisiton and allow the lugs to move outwards and release the plug (FIG. 12).
None of the known prior art patents disclose a device having an open bore therethrough and an abrupt stop shoulder surrounding the bore for engaging and stopping a well tool having key means thereon with an abrupt stop shoulder, this tool stopping device having remotely operated means for disengaging the stop shoulder on the keys from the stop shoulder in the device to, thus, release the well tool for movement past and beyond the device.